Search

The Polymer group of the Faculty of Technology and Metallurgy University of Belgrade deals with environment-sensitive hydrogel as carriersfor biomedical applications, including drug delivery, wound healing, and regenerative medicine. The first hydrogel generation synthesized in our labs was discs made of polyacrylamide and its derivatives. The synthesis was at higher temperatures (50 °C), with traditional crosslinker, N, N’-methylenebisacrylamide, and persulphate/pyrosulphate as initiator. Due to the growing demands for environmental sustainability, the general approach changed to reduce petrochemical raw materials and prepare eco-friendly materials focusing on 1) renewable polymers, initiators, and crosslinkers and 2) the application of simple, cost-effective, and eco-friendly approaches in hydrogel synthesis. To obtain the second hydrogel generation, we use renewable polymers: polysaccharides, proteins, and polyhydroxyalkanoates [1]. Still, the mechanical strength was weak. Hence, the applicationof carboxylic acids, methacrylic and itaconic, and N-isopropyl acrylamide improves mechanical properties and enhances the environmental stimuli of the carriers. Instead of traditional crosslinkers -organic molecules, we gave the advantage to plant extracts like genipin, sodium tripolyphosphate, citric acid, and calcium chloride. We made beads, microgels, aerogels, discs, films, and cylinders sensitive to pH, temperature, magnetic field, or specific molecules such as glucose. Facing an everyday challenge, improving drug delivery routes, especially for poorly water-soluble drugs, and finding an alternative to traditional antibiotics, encapsulation, and controlled release remain a challenge. Therefore, we used a mild condition (e.g., deep coating) to encapsulate/release traditional water-soluble and poorly water-soluble drugs, proteins, phenolic compounds, or supercritical carbon dioxide (scCO2) for thymol, carvacrol, and eugenol, a promising alternative for traditional antib

This study investigates pharmaceutical polymers (Soluplus®, HPMCAS, and Eudragit® E100) and supercritical CO2-assisted process for preparation of floating valsartan delivery systems. Tested process (at pressure of 30 MPa and temperature of 100 °C during 2 h) enabled preparation of stable porous valsartan formulations which was confirmed with FESEM and mercury intrusion porosimetry analysis. The bulk density of obtained formulations was lower than 550 kg/m3. FTIR, DSC, and PXRD analysis indicated that there was no chemical interaction between the drug and polymers and that amorphous solid dispersions were obtained. Formulations with Soluplus® and HPMCAS retained its buoyancy in 0.1 M HCl for longer than 24 h, while formulation with Eudragit® E100 retained its buoyancy up to 2 h. Controlled valsartan release was influenced by solubility of polymers in the tested release medium, which was confirmed by UV/VIS spectroscopy. The obtained results provided framework for further development of floating drug delivery system using an environmental friendly process.

The present paper reports on pectin based films modified with carboxymethyl cellulose intended for food packaging. The films are prepared by solvent-casting method with different carboxymethyl cellulose content and cross-linker concentration (Ca2+ ions) in the presence of glycerol as a plasticizer. FT-IR spectra of the prepared films propose that carboxyl group from pectin are mainly involved in interactions with CMC, whereas -OH groups are mainly involved in self-associated hydrogen bonding of neat polymers. Further, an addition of carboxymethyl cellulose improved mechanical properties compared to pure pectin films, while TGA analysis confirmed satisfying thermal stability regarding their potential application as packaging material. Finally, water vapor permeability values are in the range of 1.32x10(-7) up to 2.03x10(-7) wg/m h Pa.

With the excessive risks that are present in today's environment, it is of great importance to treat wastewaters before their discharge in water streams. One of the everyday challenges is design of a low-cost and environmentally friendly sorbent such as hydrogel based on chitosan, itaconic and methacrylic acid that can remove wide range of textile dyes. In the present study, this hydrogel has been utilized for investigation of removal of three different azo dyes from simulated textile wastewater: C.I. Basic Blue 9, C.I. Basic Red 1 and C.I. Acid Orange 7. It was found that pH value of the solution had significant effect on dye sorption. Removal of basic dyes was successful at higher pH values, while sorption of acid dye was possible only at low pH value of solution. Simulated textile wastewater is a complex system with various salts, acids and polymers present beside dyes. Regardless of these components, excellent sorption capacity was achieved (more than 80% of dyes were removed), which makes this hydrogel attractive for use under real conditions., Zbog sve više rizika koji se javljaju po životnu sredinu, veoma je važno prečistiti otpadne vode pre njihovog ispuštanja u vodotokove. Zato je jedan od izazova današnjih istraživanja dizajn jeftinog i ekološki prihvatljivog sorbenta, kao što je hidrogel na bazi hitozana, itakonske i metakrilne kiseline, koji može da ukloni širok spektar tekstilnih boja. U ovom radu je korišćen hidrogel za ispitivanje uklanjanja tri različite azo boje iz simulirane otpadne vode iz tekstilne industrije: C.I. Basic Blue 9, C.I. Basic Red 1 i C.I. Acid Orange 7. Utvrđeno je da pH vrednost rastvora značajno utiče na sorpciju boja. Uklanjanje baznih boja je uspešno pri višim pH vrednostima, dok je sorpcija kisele boje moguća samo pri niskoj pH vrednosti rastvora. Simulirana otpadna voda iztekstilne industrije je složen sistem sačinjen od različith soli, kiselina i polimera koji su prisutni pored boja za tekstil. Bez obzira na ove komponente, ostvaren je odličan kapacitet sorpcije (uklonjeno je više od 80% boje iz rastvora), što ovaj hidrogel čini atraktivnim za upotrebu u realnim sistemima.

Supercritical carbon dioxide (scCO(2)) technology was used for preparation of functional pH sensitive chitosan-based aerogels characterized with micron size pores and their impregnation with thymol as a natural bioactive substance. Hydrogels based on chitosan, itaconic and methacrylic acids were transformed to alcogels and dried in the air or with scCO(2) to obtain xero- and aerogels, respectively. Applying 10 min of static and 120 min of dynamic scCO(2) drying at 11 MPa and 45 degrees C followed with the decompression at a rate of 1 MPa/min yielded an advantageous aerogel with favorable swelling kinetics and elasticity, compared to the xerogel and aerogels obtained at other decompression rates and drying times. This aerogel was successfully loaded with thymol (up to 4.6 wt.%) using supercritical scCO(2) at 10 MPa and 35 degrees C. In vitro studies of swelling in PBS at 37 degrees C indicated a great potential of the obtained stimuli-responsive chitosan gels for topical administration of thymol known for antimicrobial, antioxidant and anti-inflammatory activities. POLYM. ENG. SCI., 58:2192-2199, 2018.

Cilj ove doktorske disertacije je da se ispitaju mogućnosti imobilizacije nanočestica titan-dioksida (TiO2) na hidrogelove kao nosače i fotodegradacija boja za tekstil iz vodenih rastvora pomoću titan-dioksid/hidrogel nanokompozita za potrebe prečišćavanja otpadnih voda iz tekstilne industrije. U radu su korišćene dve vrste TiO2 nanočestica: (a) sintetisane koloidne nanočestice TiO2, dobijene kiselom hidrolizom titan-tetrahlorida; (b) komercijalno dostupne nanočestice TiO2 (Degussa P25), radi poređenja fotokatalitičke aktivnosti. Kao nosači nanočestica TiO2 pripremljeni su sledeći hidrogelovi: (a) hidrogelovi hitozana, itakonske kiseline i metakrilne kiseline sintetisani radikalnom polimerizacijom; (b) mikročestice hitozana i poli(metakrilne kiseline), po prvi put sintetisane inverznom suspenzionom polimerizacijom; (c) interpenetrirajuće mreže (IPM) natrijum-alginata i delimično neutralisane poli(metakrilne kiseline) dobijene radikalnom polimerizacijom i naknadnim umrežavanjem jonima kalcijuma. Imobilizacijom nanočestica titan-dioksida na hidrogelove dobijeni su TiO2/hidrogel nanokompoziti, koji su okarakterisani i ispitana je njihova fotokatalitička aktivnost. Prisustvo nanočestica TiO2 na/u hidrogelovima je potvrđeno energetskom disperzionom spektroskopijom (EDX). Skenirajuća elektronska mikroskopija (SEM) je pokazala da hidrogelovi hitozana i interpenetrirajuće mreže natrijum-alginata imaju poroznu strukturu. Eksperimentima bubrenja i reološkim ispitivanjima je potvrđeno da veličina pora, kinetika bubrenja i mehanička jačina zavise od sastava hidrogelova, stepena umreženja, prisustva i vrste imobilisanih nanočestica TiO2. SEM analiza i optička mikroskopija su pokazale da mikročestice hitozana imaju sferičnu strukturu. Infracrvenom spektroskopijom sa Fourier-ovim transformacijama (FTIR) je utvrđeno da su u polimernu mrežu nosača ugrađene sve komponente prisutne tokom sinteze. Termogravimetrijskom analizom (TGA) i skenirajućom kalorimetrijom (DSC) je zaključeno da, The aim of this Ph.D. thesis was to investigate the possibility of immobilization of titanium dioxide (TiO2) nanoparticles onto/into hydrogels as carriers, as well as the photodegradation of textile dyes from aqueous solutions by titanium dioxide/hydrogel nanocomposites that could be exploited for treatment of textile effluents. Two types of TiO2 nanoparticles were used: (a) freshly synthetized colloidal TiO2 nanoparticles, prepared by acid hydrolysis of titanium tetrachloride; (b) commercially available TiO2 nanoparticles (Degussa P25), which were used for comparison of photocatalytic activity. The following hydrogels have been synthetized as a carriers for TiO2 nanoparticles: (a) chitosan, itaconic acid and methacrylic acid hydrogels synthesized by free radical polymerization; (b) chitosan and poly(methacrylic acid) microparticles (Ch/PMA), which were synthesized for the first time by inverse suspension polymerization; (c) sodium alginate and partially neutralized poly(methacrylic acid) interpenetrating polymer networks (IPN) obtained by free radical polymerization followed by additional cross-linking of sodium alginate with calcium ions. TiO2/hydrogel nanocomposites were obtained by immobilization of TiO2 nanoparticles onto/into hydrogels, which were afterwards characterized and their photocatalytic activity was tested. The presence of TiO2 nanoparticles onto/into hydrogels was confirmed by energy dispersive spectroscopy (EDX). The porous structure of the chitosan-based hydrogels and sodium alginate-based interpenetrating networks was observed by SEM analysis. Swelling experiments and rheological studies showed that the pore size, swelling kinetics and mechanical strength depend on the hydrogel composition, degree of crosslinking, presence of TiO2 nanoparticles and the type of immobilized TiO2 nanoparticles. SEM analysis and optical microscopy revealed that chitosan microparticles have a spherical structure. Infrared spectroscopy with Fourier transformation (FTIR

The aim of this Ph.D. thesis was to investigate the possibility of immobilization of titanium dioxide (TiO2) nanoparticles onto/into hydrogels as carriers, as well as the photodegradation of textile dyes from aqueous solutions by titanium dioxide/hydrogel nanocomposites that could be exploited for treatment of textile effluents. Two types of TiO2 nanoparticles were used: (a) freshly synthetized colloidal TiO2 nanoparticles, prepared by acid hydrolysis of titanium tetrachloride; (b) commercially available TiO2 nanoparticles (Degussa P25), which were used for comparison of photocatalytic activity. The following hydrogels have been synthetized as a carriers for TiO2 nanoparticles: (a) chitosan, itaconic acid and methacrylic acid hydrogels synthesized by free radical polymerization; (b) chitosan and poly(methacrylic acid) microparticles (Ch/PMA), which were synthesized for the first time by inverse suspension polymerization; (c) sodium alginate and partially neutralized poly(methacrylic acid) interpenetrating polymer networks (IPN) obtained by free radical polymerization followed by additional cross-linking of sodium alginate with calcium ions. TiO2/hydrogel nanocomposites were obtained by immobilization of TiO2 nanoparticles onto/into hydrogels, which were afterwards characterized and their photocatalytic activity was tested. The presence of TiO2 nanoparticles onto/into hydrogels was confirmed by energy dispersive spectroscopy (EDX). The porous structure of the chitosan-based hydrogels and sodium alginate-based interpenetrating networks was observed by SEM analysis. Swelling experiments and rheological studies showed that the pore size, swelling kinetics and mechanical strength depend on the hydrogel composition, degree of crosslinking, presence of TiO2 nanoparticles and the type of immobilized TiO2 nanoparticles. SEM analysis and optical microscopy revealed that chitosan microparticles have a spherical structure. Infrared spectroscopy with Fourier transformation (FTIR, Cilj ove doktorske disertacije je da se ispitaju mogućnosti imobilizacije nanočestica titan-dioksida (TiO2) na hidrogelove kao nosače i fotodegradacija boja za tekstil iz vodenih rastvora pomoću titan-dioksid/hidrogel nanokompozita za potrebe prečišćavanja otpadnih voda iz tekstilne industrije. U radu su korišćene dve vrste TiO2 nanočestica: (a) sintetisane koloidne nanočestice TiO2, dobijene kiselom hidrolizom titan-tetrahlorida; (b) komercijalno dostupne nanočestice TiO2 (Degussa P25), radi poređenja fotokatalitičke aktivnosti. Kao nosači nanočestica TiO2 pripremljeni su sledeći hidrogelovi: (a) hidrogelovi hitozana, itakonske kiseline i metakrilne kiseline sintetisani radikalnom polimerizacijom; (b) mikročestice hitozana i poli(metakrilne kiseline), po prvi put sintetisane inverznom suspenzionom polimerizacijom; (c) interpenetrirajuće mreže (IPM) natrijum-alginata i delimično neutralisane poli(metakrilne kiseline) dobijene radikalnom polimerizacijom i naknadnim umrežavanjem jonima kalcijuma. Imobilizacijom nanočestica titan-dioksida na hidrogelove dobijeni su TiO2/hidrogel nanokompoziti, koji su okarakterisani i ispitana je njihova fotokatalitička aktivnost. Prisustvo nanočestica TiO2 na/u hidrogelovima je potvrđeno energetskom disperzionom spektroskopijom (EDX). Skenirajuća elektronska mikroskopija (SEM) je pokazala da hidrogelovi hitozana i interpenetrirajuće mreže natrijum-alginata imaju poroznu strukturu. Eksperimentima bubrenja i reološkim ispitivanjima je potvrđeno da veličina pora, kinetika bubrenja i mehanička jačina zavise od sastava hidrogelova, stepena umreženja, prisustva i vrste imobilisanih nanočestica TiO2. SEM analiza i optička mikroskopija su pokazale da mikročestice hitozana imaju sferičnu strukturu. Infracrvenom spektroskopijom sa Fourier-ovim transformacijama (FTIR) je utvrđeno da su u polimernu mrežu nosača ugrađene sve komponente prisutne tokom sinteze. Termogravimetrijskom analizom (TGA) i skenirajućom kalorimetrijom (DSC) je zaključeno da

The present paper deals with removal and photocatalytic degradation of the textile dyes by TiO2 nanoparticles immobilized onto chitosan-based microparticles. The microparticles composed of chitosan (Ch) and poly(methacrylic acid) (PMA) were fabricated for the first time by inverse suspension polymerization. They were utilized for colloidal TiO2 nanoparticles immobilization, synthetized by acidic hydrolysis of TiCl4. To evaluate the potential application of Ch/PMA/TiO2 microparticles for treatment of textile wastwaters, their photocatalytic activity was examined by degradation assessment of three different groups of anionic azo dyes in aqueous solutions under solar light simulating source. FTIR analysis revealed that Ch and PMA were incorporated in the polymer network. SEM and optical microscopy confirmed their spherical shape. Under illumination, Ch/PMA/TiO2 microparticles completely removed dyes C.I. Acid Orange 7, C.I. Acid Red 18, C.I. Acid Blue 113, C.I. Reactive Black 5, C.I. Direct Blue 78, while removal degree of C.I. Reactive Yellow 17 was 75%. It was found that pH had significant influence on the photocatalytic activity of Ch/PMA/TiO2 microparticles. Increase of solution pH from acidic to alkaline, lead to decrease in photodegradation rate of C.I. Acid Orange 7 during the first hours of illumination. After three illumination cycles, removal degree of C.I. Acid Orange 7 was maintained at remarkably high level (95% at pH 5.60 and 100% at pH 2.00 and 8.00), indicating that microparticles could be reused without significant loss of photocatalytic efficiency.

The present work was aimed to study swelling kinetics of polylactic acid (PLA) and its impregnation with thymol in supercritical carbon dioxide (scCO2) medium. The influences of temperature and soaking time on the swelling kinetics and impregnation yield of PLA cylindrical disc and film were investigated. Swelling experiments were performed in a high pressure view cell at 10 MPa and temperatures of 40°C, 60°C and 75°C for 2 to 24 h. On the basis of swelling kinetics, pressure of 10 MPa and temperature of 40°C were chosen for supercritical solvent impregnation (SSI) of the PLA samples during 2 to24 h. The highest swelling extent was observed for the PLA monolith after 24 h treatment with pure scCO2 (7.5%) and scCO2 with thymol (118.3%). It was shown that sufficiently high amount of thymol can be loaded into both PLA monolith and film using SSI after only 2 h (10.0% and 6.6%, respectively). Monolith and film of PLA impregnated with thymol could be suitable for active food packaging and sterile medical disposables., Prikazana studija je namenjena ispitivanju kinetike bubrenja polilaktida (PLA) i njegovoj impregnaciji timolom u natkritičnom ugljenik(IV)-oksidu (nkCO2). Praćen je uticaj temperature i operativnog vremena na kinetiku bubrenja i prinos impregnacije PLA cilindričnog diska i filma. Eksperimenti bubrenja su izvedeni u ćeliji za rad pod visokim pritiscima na 10 MPa and 40°C, 60°C i 75°C od 2 h do 24 h. Na osnovu kinetike bubrenja, natkritična impregnacija uzoraka PLA timolom je izvedena na pritisku od 10 MPa i temperaturi od 40°C tokom 2 do 24 h. Najveći stepen bubrenja je imao PLA disk na 10 MPa i 40°C nakon 24 h (7,5%) u sistemu sa čistim nkCO2 i u sistemu sa timolom (118,3%). Pokazano je da se dovoljno visok prinos impregnacije timola može postići nakon 2 h (10,0% za disk i 6,6% za film). PLA u formi diska i filma impregnirani timolom su pogodni materijali za aktivno pakovanje hrane i za sterilni medicinski pribor.

The aim of this Ph.D. thesis was to investigate the possibility of immobilization of titanium dioxide (TiO2) nanoparticles onto/into hydrogels as carriers, as well as the photodegradation of textile dyes from aqueous solutions by titanium dioxide/hydrogel nanocomposites that could be exploited for treatment of textile effluents. Two types of TiO2 nanoparticles were used: (a) freshly synthetized colloidal TiO2 nanoparticles, prepared by acid hydrolysis of titanium tetrachloride; (b) commercially available TiO2 nanoparticles (Degussa P25), which were used for comparison of photocatalytic activity. The following hydrogels have been synthetized as a carriers for TiO2 nanoparticles: (a) chitosan, itaconic acid and methacrylic acid hydrogels synthesized by free radical polymerization; (b) chitosan and poly(methacrylic acid) microparticles (Ch/PMA), which were synthesized for the first time by inverse suspension polymerization; (c) sodium alginate and partially neutralized poly(methacrylic acid) interpenetrating polymer networks (IPN) obtained by free radical polymerization followed by additional cross-linking of sodium alginate with calcium ions. TiO2/hydrogel nanocomposites were obtained by immobilization of TiO2 nanoparticles onto/into hydrogels, which were afterwards characterized and their photocatalytic activity was tested. The presence of TiO2 nanoparticles onto/into hydrogels was confirmed by energy dispersive spectroscopy (EDX). The porous structure of the chitosan-based hydrogels and sodium alginate-based interpenetrating networks was observed by SEM analysis. Swelling experiments and rheological studies showed that the pore size, swelling kinetics and mechanical strength depend on the hydrogel composition, degree of crosslinking, presence of TiO2 nanoparticles and the type of immobilized TiO2 nanoparticles. SEM analysis and optical microscopy revealed that chitosan microparticles have a spherical structure. Infrared spectroscopy with Fourier transformation (FTIR, Cilj ove doktorske disertacije je da se ispitaju mogućnosti imobilizacije nanočestica titan-dioksida (TiO2) na hidrogelove kao nosače i fotodegradacija boja za tekstil iz vodenih rastvora pomoću titan-dioksid/hidrogel nanokompozita za potrebe prečišćavanja otpadnih voda iz tekstilne industrije. U radu su korišćene dve vrste TiO2 nanočestica: (a) sintetisane koloidne nanočestice TiO2, dobijene kiselom hidrolizom titan-tetrahlorida; (b) komercijalno dostupne nanočestice TiO2 (Degussa P25), radi poređenja fotokatalitičke aktivnosti. Kao nosači nanočestica TiO2 pripremljeni su sledeći hidrogelovi: (a) hidrogelovi hitozana, itakonske kiseline i metakrilne kiseline sintetisani radikalnom polimerizacijom; (b) mikročestice hitozana i poli(metakrilne kiseline), po prvi put sintetisane inverznom suspenzionom polimerizacijom; (c) interpenetrirajuće mreže (IPM) natrijum-alginata i delimično neutralisane poli(metakrilne kiseline) dobijene radikalnom polimerizacijom i naknadnim umrežavanjem jonima kalcijuma. Imobilizacijom nanočestica titan-dioksida na hidrogelove dobijeni su TiO2/hidrogel nanokompoziti, koji su okarakterisani i ispitana je njihova fotokatalitička aktivnost. Prisustvo nanočestica TiO2 na/u hidrogelovima je potvrđeno energetskom disperzionom spektroskopijom (EDX). Skenirajuća elektronska mikroskopija (SEM) je pokazala da hidrogelovi hitozana i interpenetrirajuće mreže natrijum-alginata imaju poroznu strukturu. Eksperimentima bubrenja i reološkim ispitivanjima je potvrđeno da veličina pora, kinetika bubrenja i mehanička jačina zavise od sastava hidrogelova, stepena umreženja, prisustva i vrste imobilisanih nanočestica TiO2. SEM analiza i optička mikroskopija su pokazale da mikročestice hitozana imaju sferičnu strukturu. Infracrvenom spektroskopijom sa Fourier-ovim transformacijama (FTIR) je utvrđeno da su u polimernu mrežu nosača ugrađene sve komponente prisutne tokom sinteze. Termogravimetrijskom analizom (TGA) i skenirajućom kalorimetrijom (DSC) je zaključeno da

An interpenetrating polymer network (IPN) based on the sodium alginate (A) and partially neutralized poly(methacrylic acid) (MAA) was prepared by free radical polymerization followed by additional cross-linking of sodium alginate with calcium ions. Obtained material (A/MAA IPN) was characterized by FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy, and rheological measurements. Swelling behavior of synthetized IPN has been also investigated. TiO2 nanoparticles (TiO2 NPs) were immobilized onto A/MAA IPN by dip-coating method and obtained TiO2/IPN nanocomposite was used for removal of the methylene blue (MB) from aqueous solution. The photodegradation (under illumination) and sorption (in the dark) processes for dye removal were monitored through decrease of dye concentration in the solution by UV/VIS spectrometer. The TiO2/IPN nanocomposite sorbed approximately 93% of the MB from a 10 mg L-1 MB solution in the dark, but no degradation occurred. Likewise, more than 93% of dye was removed after 8 h of illumination. However, after 24 h of illumination, the samples were discolored indicating that dye molecules were successfully degraded. Thus, the TiO2/IPN nanocomposite could be utilized in the photodegradation-sorption process for the abatement of pollutants in water. POLYM. ENG. SCI., 55:2511-2518, 2015.

An interpenetrating polymer network (IPN) based on the sodium alginate (A) and partially neutralized poly(methacrylic acid) (MAA) was prepared by free radical polymerization followed by additional cross-linking of sodium alginate with calcium ions. Obtained material (A/MAA IPN) was characterized by FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy, and rheological measurements. Swelling behavior of synthetized IPN has been also investigated. TiO2 nanoparticles (TiO2 NPs) were immobilized onto A/MAA IPN by dip-coating method and obtained TiO2/IPN nanocomposite was used for removal of the methylene blue (MB) from aqueous solution. The photodegradation (under illumination) and sorption (in the dark) processes for dye removal were monitored through decrease of dye concentration in the solution by UV/VIS spectrometer. The TiO2/IPN nanocomposite sorbed approximately 93% of the MB from a 10 mg L-1 MB solution in the dark, but no degradation occurred. Likewise, more than 93% of dye was removed after 8 h of illumination. However, after 24 h of illumination, the samples were discolored indicating that dye molecules were successfully degraded. Thus, the TiO2/IPN nanocomposite could be utilized in the photodegradation-sorption process for the abatement of pollutants in water. POLYM. ENG. SCI., 55:2511-2518, 2015. (c) 2015 Society of Plastics Engineers

Stimuli responsive pH- and temperature-sensitive hydrogel drug delivery systems, as those based on N-isopropylacrylamide (NiPAAm) and itaconic acid (IA), have been attracting much of the attention of the scientific community nowadays, especially in the field of drug release. By adjusting comonomer composition, the matrix is enabled to protect the incorporated protein in the highly acidic environment of upper gastrointestinal tract and deliver it in the neutral or slightly basic region of the lower intestine. The protein/poly(NiPAAm-co-IA) hydrogels were synthetized by free radical crosslinking copolymerization and were characterized concerning their swelling capability, mechanical properties, and morphology. The pore structure and sizes up to 1.90 nm allowed good entrapment of lipase molecules. Model protein, lipase from Candida rugosa, was entrapped within hydrogels upon mild conditions that provided its protection from harmful environmental influences. The efficiency of the lipase entrapment reached 96.7%, and was dependent on the initial concentration of lipase solution. The swelling of the obtained hydrogels in simulated pH and temperature of gastrointestinal tract, the lipase entrapment efficiency, and its release profiles from hydrogels were investigated as well.